Facsimile transmission system

ABSTRACT

A facsimile system for transferring graphical information between two remotely located machines each controlled to operate both as a transmitter and a receiver and comprising storage means in the form of an orbitally movable magnetic tape for retaining a magnetic image of graphical information to be transferred. An image forming means optically scans an input medium such as a document and forms a magnetic image on the tape of graphical information from the input medium when the machine is to transmit. Then a signal generating means scans the magnetic image on the tape and provides signals indicative of the graphical information for transmission by wire or radiowave. When the machine is to operate as a receiver, a signal detecting means receives transmitted signals indicative of graphical information, transforms the signals, and utilizes them to form a magnetic image of the graphical information on the tape. A transfer means applies magnetic toner particles to the magnetic image on the tape and then transfers the toner particles to a copy medium such as paper.

United States Patent 1191 Rait et al.

[ July 31, 1973 FACSIMILE TRANSMISSION SYSTEM Inventors: Joseph M. Rait, Buffalo; Alexander Scott Gilmour, Jr., Williamsville; Edward C. Sellers, Buffalo; Edward Lindberg, Bowmansville, all of NY.

Assignee: Pelorex Corp., Buffalo, NY.

Filed: Feb. 14, 1972 Appl. No.: 225,841

US. Cl. l78/6.6 A, 346/74 ES, 346/74 MP Int. Cl G0ld 15/02, H04n 1/10, G1 1b 5/02 Field of Search l78/6.6 A;

' 346/74 ES, 74 MP References Cited UNITED STATES PATENTS 8/1972 Nishiyama et al. 17816.6 A 5/1965 Rheinfrank 346/74 MP 1/1961 Epstein et a1 346/74 MP Primary Examiner-James W. Moffitt Att0rneyConrad Christel et al.

[ 1 ABSTRACT A facsimile svstem for transfemng graphicalinformation between two remotely located machines each controlled to operate both as a transmitter and a receiver and comprising storage means in the form of an orbitally movable magnetic tape for retaining a magnetic image of graphical information to be transferred. An image forming means optically, scans an input medium such as a document and forms a magnetic image on the tape of graphical information from the input medium when the machine is to transmit. Then a signal generating means scans the magnetic image on the tape and provides signals indicative of the graphical information for transmission by wire or radiowave. When the machine is to operate as a receiver, a signal detecting means receive s transmitted signals indicative of graphical information, transforms the signals, and utilizes them to form a magnetic image of the graphical information on the tape. A transfer means applies magnetic toner particles to the magnetic image on the tape and then transfers the toner particles to a copy medium such as paper.

11 Claims, 4 Dravving Figures -roNER I 4'2 1 FACSIMILE TRANSMISSION SYSTEM BACKGROUND OF THE INVENTION It would be highly desirable to provide apparatus for such a' system whereby the original can be removed from the apparatus at the transmitting station prior to the end of the operation producing hard copies at either station. Furthermore, it would be highly desirable to provide such apparatus capable of making multiple copies at either or both stations at a relatively high rate of speed and which also is simple in construction and operation.

SUMMARY OF THE INVENTION The present invention provides a facsimile system for transferring graphical information between two machines coupled by a transmission medium and each capable of functioning both as a transmitter and a receiver and including storage means of magnetizable material for retaining a magnetic image of graphical information to be transferred. Graphical information on an input medium is optically scanned and a magnetic image thereof is formed on the storage means. A signal generating means scans the magnetic image and produces signals indicative of the graphical information for transmission through the medium. A signal detecting BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of apparatus according to the present invention for use in facsimilie transmission;

FIG. 2 is a graph illustrating signal waveforms occurring at various locations in the apparatus of FIG. 1;

FIG. 3 is a diagrammatic view of magnetic image scanning and forming means according to one embodiment of the present invention for use in the apparatus of FIG. 1; and

FIG. 4 is a diagrammatic view of magnetic image scanning and forming means according to another embodiment of the present invention for use in the apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS A facsimile system for transferring graphical information according to the present invention includes two machines each similar to that of FIG. 1 connected together by a suitable transmission medium. The two machines can be connected by ordinary telephone lines, by coaxial cable, or by various radio wave communication techniques. Both machines are capable of functioning as a transmitter and as a receiver to permit a reversible transfer of graphical information between the two machines.

Referring now in detail to FIG. 1, there is shown a machine 10 which is one of two identical machines included in the system of the present invention and which is capable of operating both as a transmitter and as a 2 receiver. The apparatus 10 comprises a storage'means 12 of magnetizable material for retaining a magnetic image of the graphical information to be transferred. In preferred form storage means 12 comprises an orbitally movable magnetically retentive member capable of surface magnetization in the form of a tape. In the present illustration tape 12 comprises a suitable base or substrate having a coating of iron oxide and zinc oxide and possibly a thin overcoat of suitable material as will be described in detail hereafter. The endless tape 12 is trained around four supporting rollers l3, l4, l5 and 16 which define an orbit for tape 12. Rollers 13-16 together with suitable drive means (not shown) to which they are coupled comprise a motive means for causing relative displacement between tape 12 and the other elements of the apparatus of the present invention. When the apparatus of FIG. 1 is to function as a transmitter, an optical image of graphical information from aninput medium 18, for example a document, is transformed to an electrostatic image on storage means .or tape 12 by a lens 20 which directs light rays from medium 18, which would be illuminated, onto the surface of tape 12 and by an electrostatic charging unit 21 which operates on tape 12 prior to its reception of light rays from the medium 18. Charging apparatus is conventional in form and being readily commercially available and well-known to those skilled in the art, a detailed description thereof is deemed to be unnecessary. Suffice it to say, the apparatus 21 charges the zinc oxide layer of tape 12 by using a potential of about minus 5,000 volts to place a negative charge on the outer surface of tape 12, as it is viewed in FIG. 1, and by using a potential of about plus 5,000 volts to place a positive charge on the inner surface of tape 12. In addition, when more than one copy is to be made, charging apparatus 12 operates only during production of the first copy as will be described in detail hereafter. The electrostatically charged tape is moved past the image of light rays directed through lens 20 from the original 18 and in synchronism with scan of original 18. When the light rays reach the outer surface of tape 12, the high light level portions of the image discharge the zinc oxide while the portions of the tape contacted by the low light level portions of the image remain charged. An electrostatic image thus is formed on the surface of tape 12, and this image formation likewiseis required only during production of the first of a number of duplicate copiesas will be described hereafter.

The apparatus of the present invention further comprises means 25 for applying magnetic toner particles to storage means or tape 12 in a manner such that the particles adhere to storage means 12 in the form of an image corresponding to the image already present thereon. The toner particles, as they are known in the art, are in the form of a pigmented powder which when applied to tape 12 provides a powder image by means of adherance or attraction to the electrostatic image. The toner particles for use in the apparatus of the present invention have an electrostatically attractive component, a magnetic component, and a resinous component to facilitate subsequent fixing to the copy medium. A preferred form of magnetic toner particles found to perform satisfactorily are those commerically available under the name Tribofax No. 213. Toner applying means 25, shown schematically in FIG. 1, can be of several known varieties readily familiar to those skilled in the art. For example, means 25 can comprise a container including a mixture of the magnetic toner particles and kerosene floated on water. The toner particles are dispersed in the kerosene and become concentrated at the bottom of the kerosene at the interface with the water. The tape 12 is moved through the dispersed mixture and passed through a kerosene rinse to remove excess toner particles. in another form, means 25 can comprise a container including a mixture of toner particles and kerosene, the toner particles settling to the bottom of the container to form a high density collection thereof. A first roller would be included to bring the mixture into contact with the tape 12, especially the high density toner particles, and a second roller provided for rinsing tape 12 with the kerosene.

The apparatus of F IG. 1 further comprises magnetizing means for applying a continuous magnetic recording to tape 12. A recording head includes a core 30 around which is wound a coil 31 connected by leads to a source of magnetizing current 34. Core 30 of the magnetizing means is positioned relative to tape 12 so as to operate thereon after toner particles are applied by the apparatus 25 to tape 12. Core 30 is positioned in the apparatus so that the magnetizing means applies a continuous magnetizing current to tape 12 in a direction, as viewed in FIG. 1, from the inner surface thereof through the tape 12. Core 30 is of a size sufficient to extend along the entire width of tape 12. Source 34 provides a periodic, such as sinusoidial or pulsed, signal for driving the recording head, the frequency depending upon the degree of resolution desired for the recording whereby a continuous uniform magnetic recording is placed on tape 12. This recording takes the form of thin, closely spaced magnetic lines covering all parts of the image area.

By way of illustration, a core 30 was employed having a gap length of approximately 0.001 inch and having coil 31 wound to provide 6 to ampere turns. To achieve the desired degree of resolution in the recording and resulting copy, it was found that the lines of the recording placed on tape 12 should be spaced apart a distance of 3 mils. This spacing was obtained by driving the recording head with a sinusoidial signal having a frequency of about 1,000 cycles and by moving tape-l2 at a speed of about 3 inches per second with tape 12 having a thickness of about 2 mils. I

The apparatus further comprises demagnetizing or magnetic erasing means in the form of a core 38 around. which is wound a coil 39 which, in turn, is connected sulting in selective erasing of tape 12 to form a magnetic image corresponding to the electrostatic image. The demagnetizing means or selective erase head is energized only during the first cycle of operation producing the first copy when multiple copies are to be made. Although source 42 can provide either a.c. or do. excitation of the erase head, alternating current at a frequency of approximately 100 kilohertz has been found to provide desirable results.

The apparatus of the present invention further comprises means including roller 45 for transferring the magnetic toner particles on tape 12 to a copy medium such as a paper indicated at 48 in F 1G. 1. By virtue of the arrangement of the present invention, a copy of the original is made and the magnetic image remains on tape 12. Roller 45 is coupled to a suitable drive means (not shown) which roller 45 is in close proximity to and in operative association with roller 13. Rollers l3 and 45 rotate in opposite directions and press or urge tape 12, i.e., the surface of tape 12 on which the toner particles are present, into intimate contact with paper 48. The transfer of toner particles is by friction and is believed to be enhanced by the porosity of the paper surface which serves to collect the toner particles. The toner transfer may be enhanced if paper 48 is given an electrostatic charge first before entering rollers 13 and 45. Rollers l3 and 45 preferably should have hard outer surfaces and be springloaded toward their respective positions.

After paper 48 has received the toner particles it is transferred by the apparatus to a conventional fusing unit indicated generally at 50 in FIG. 1 for fixing the toner particles to paper 48. Unit 50 functions to apply heat, such as from a lamp, to the toner particles thereby causing the resinous component of the particles to fuse or permanently bond the particles to the copy medium upon subsequent cooling. Residual toner particles are removed from storage means or tape 12 by means of a roller indicated schematically at 52 which can be provided with an outer surface of felt and which is continually cleaned. The apparatus also includes a demagnetizing means or magnetic erase head which operates on tape 12 when the magnetic image or recording thereon is no longer needed. In this particular illustration, a core 54 is positioned near tape 12 and has wound thereon a coil 55 which is connected through leads to a source of demagnetizing or erase current 56. Source 56 is operated selectively to energize the erase head only when the magnetic image on tape 12 is to be removed such as when only one copy is wanted or after a desired number of copies havebeen produced.

The apparatus would include, in addition, a suitable control system for controlling the heads 30, 38 and 54 as well as charging apparatus 21 and the scanning means during each cycle of operation of the apparatus as will be described in further detail presently. Also there woud be provided control means for feeding copy media or paper sheets through the apparatus successively as in conventional photocopying apparatus.

According to the foregoing illustration, a magnetic image of graphical information is formed on tape 12 by slectively erasing a continuous magnetic recording previously applied to tape 12. Alternatively, the magnetic image can be formed on tape 12 by other methods such as by directly selectively recording magnetically on tape 12 thereby allowing tape 12 to be merely of magnetizable material. For a more detailed description of these and additional methods and apparatus for forming a magnetic image of graphical information on a storage means like tape 12, reference can be made to the pending US. patent application of Rait, Gilmour and Sellers Ser. No. 163,264 filed July 16, 1971 and assigned to the assignee of the present invention.

In the apparatus-l0 of FIG. 1, block 60 schematically designates means for scanning the magnetic image on tape 12 when the apparatus is to'operate as a transmitter and for forming a magnetic image on tape 12 when the apparatus 10 is to operate as a receiver. In

particular, means 60 scans the magnetic image on storage means such as tape 12 and provides output electri cal signals corresponding to the graphical information, for transmission, when the apparatus 10 is to function as a transmitter. Means 60 also functions in response to received signals carrying graphical information to form a magnetic image of the graphical information on storage means such as tape 12 when the apparatus 10 of FIG. 1 is to function as a receiver. The particular mode of operation of means 60 is selected by a mode selection means generally designated 64 and connected in controlling relation to means 60 through lines 65a, 65b. In preferred form, means 60 comprises a magnetic record and playback head or arrangement of heads suitably synchronized and capable of high-speed, twodimensional scanning of magnetic tape 12. Various detailed examples of means 60 will be described presently.

According to a preferred mode (if the present invention, the signal appearing at the output of means 60 in FIG. I is an amplitude-modulated signal, the modulation being a function of the graphical information content of the information which is to be transmitted. In particular, waveform 66 in FIG. 2 is typical of that which is generated by means 60, and the frequency of waveform 66 is equal to the scanning rate of the head or heads of means 60 relative to tape 12. Also waveform 66 is representative of the input to means 60 when apparatus 10 operates. as a receiver. The various amplitude levels of waveform 66 correspond to the white, gray and black portions of the graphical information. In particular, the zero or minimum amplitude level can correspond to the white areas on the original 18, the peak amplitude level to the black portions of original 18, and the various intermediate levels to the different levels of gray information on original 18. In a typical specimen to be transmitted, there can be as many as six different levels of gray information. When the apparatus 10 of FIG. 1 operates as a transmitter, the amplitude-modulated waveform 66 is suitable for transmission, but to render this transmission more effective the waveform 66 is processed by additional apparatus of the present invention which now will be described.

In the apparatus 10 of FIG. 1 block 70 schematically,

designates means for converting the amplitudemodulated output signals of means 60 into coded pulses when apparatus 10 operates in the transmitting mode and for converting coded pulses into amplitudemodulated signals in the reverse direction of operation when apparatus 10 is to function as a receiver. Means 60 is connected to means 70 through lines 68a, 68b for operation in one mode, such as transmitting, and through lines 68c, 68d for operation in the other mode, such as receiving According to a preferred arrangement of the present invention, the pulses of means 70 are coded in terms of the number of pulses in a given period as determined by the amplitude level of waveform 66 produced by means 60. This can be seen by examining waveform 7 2 in FIG. 2 and its relationship to waveform 66. Alternatively, other parameters of the pulse train could be coded or modulated in terms of the amplitude variations in waveform 66. For example, the pulse'amplitude, the pulse duration, or the pulse position within a given time interval could bevaried. In preferred form, means 70 comprises an analog-to -digital and digital-to-analog converter, the particular mode of operation being externally controllable by means 64 which is connected to means 70 througha line 71. Such converters are well known to those familiar with the art and readily commercially available so a detailed description thereof is deemed to be unnecessary. Forms of converter 70 found to operate satisfactorilyin the apparatus of the present invention are commercially available from Analog Devices, Inc. of Norwood, Mass. and designated models AD C8F, ADC8I-I and ADCSU according to the speed range.

The apparatus of FIG. 1 further comprises a modem 76 which is an abbreviation for what is known in the art as a reversible modulator-demodulator. When the apparatusl0 operates as a transmitter, modem 76con'iverts the coded pulses from converter 70 illustrated as wavefrom 72, into a frequency-modulated signal such as that illustrated by waveform 80 in FIG. 2. The modu-' lation of waveform 80 is a function of the coding of the pulses in waveform 72. When the apparatus operates as a receiver, the detected frequency-modulated signal is converted by modem 76 intoa pulse waveform, similar to that ofwaveform 72. This is then converted to amplitude modulated signals by converter and fed to unit 60 for recording on tape 12. Converter 70 is connected to modem 76 through lines 77a, 77b'foroperation in one mode, such as transmitting, and through lines 77c, 77d for operation in the other mode, such as receiving. Modem 76 is externally controllably by means 64, which is connected to modem 76 through a line 78. Forms of modem 76 found to perform satisfactorily in the apparatus of the presentinvention are the Bell System 202 modem for relatively low speed operation (about 1800 bits per second) and the Bell System 303' D modem for relatively high speed operation (about 230,000 hits per second).

The apparatus of FIG. I further comprises means 84 for providing an electrical coupling between apparatus l0 and the transmission medium. Means 84" is connected to modem 76 through lines 83a, 83b. For example, means 84 can comprise an antenna and appropriate circuitry when wireless transmission is employed between transmitter and receiver. Alternatively, means 84 can comprise an impedance modifying network when a transmission line connects the transmitter and receiver. The exact nature of means 84, as determined by the particular transmission medium selected, is believed to be readily understood by those skilled in the art so that a detailed description thereof is deemed to be unnecessary.

The facsimile system of the present invention operates in the following manner. First, assume that apparatus 10 shown in FIG. 1 comprises the transmitter of the system, and that original medium or document 18 includes the graphical information which it is desired to transmit to the system receiver at some relatively remote location. Means 64 is set or activated to place the apparatus 10 in the transmitting mode of operation.

The original 18 is scanned by relative movement between it and a light source as in conventional photocopying, and tape 12 as it is moved through its orbit has an electrostatic charge applied thereto by means 21, whereupon tape 12 travels past the optical image directed by lens 20 in synchronism with the scanning of original 18. The portion of the optical image having a high light level or intensity discharges the zinc oxide on the surface of tape 12 while those portions of the surface receiving the low light level or intensity portions of the image remain charged. An electrostatic image thus is formedon the surface of tape 12 in correspon dence with or as a duplicate of the optical image received from the original 18.

As tape 12 is moved further through its orbit, the portion thereof on which the electrostatic image is present passes through the toner applying apparatus 25. The toner particles as previously described include an electrostatically attractive component whereby the particles are attracted to the electrostatically charged portions of the surface of tape 12. Upon leaving the apparatus 25, the lower surface of tape 12, as viewed in FIG. 1, has a powder image provided by the toner particles in correspondence with and as a duplicate of the electrostatic image.

Tape 12 next is moved into proximity with core 30, and source 34 delivers a periodic current at a frequency of about 1,000 cycles to apply a continuous magnetizing current to tape 12 in a direction from the inner surface thereof, as viewed in FIG. 1, to the tape. Tape 12 then has a continuous magnetic recording thereon in the form of lines closely spaced about three mils apart. Tape 12 then is passed into proximity with core 38 which when energized by source 42 applies a demagnetizing or magnetic erasing signal to tape 12, i.e., onto the surface of tape 12 on which the toner particles are present. As a result, the toner particles adhering to tape 12 by electrostatic attraction provide a magnetic shunt thereby causing selective erasing of tape 12 to form a magnetic image corresponding to or duplicating the electrostatic image.

As tape 12 and copy medium or paper 48 travel together between rollers 13 and 45, the toner particles are transferred to paper 48 to form a copy, and the magnetic image remains on tape 12 for scanning by means 60. Paper 48 having the toner particles thereon is then moved into proximity with fusing unit 50 for fixing the particles thereto.

Tape 12 travels further through its orbit toward means 60 and has thereon a magnetic image corresponding to the graphical information on medium 18. This magnetic image on tape 12 is scanned by means 60 to provide an amplitude-modulated signal such as that of waveform 66 shown in FIG. 2. The amplitudemodulated signals generated by means 60 are conducted through lines 68a, 68b to converter 70 wherein they are converted to coded pulses which then are conducted by lines 77a, 77b to modem 76 for conversion to frequency modulated signals. These signals are applied through lines 83a, 83b to coupling means 84 which inthe present illustration will be assumed to include an antenna. Thus, the apparatus of FIG. 1 operating as a transmitter ultimately generates radio waves modulated in accordance with the graphical in formation contained in original medium 18.

The magnetic image on tape 12 after being scanned by means 60 can be removed by energization of magnetic erasing head 54. Alternatively, the magnetic image can remain on tape 12 which then would be recycled to apply toner particles by means 25 for "production of additional copies on the paper 48. The toner particles, having a magnetic component, adhere to the surface of tape 12 to form a powder image thereon. During successive cycles of operation producing additional copies at the transmitter site, scanning means would be deactivated. During this production of additonal copies, the apparatus 10 can operate at a faster rate than during the first cycle because optical scanning of original 18 and operation of unit 21 are not required.v

This also permits the original 18 to be removed from the apparatus 10 during production of additional copies at the transmitter site.

The radio wave signals produced by the transmitting apparatus 10 of FIG. 1 are received by apparatus identical to that of FIG. 1 but operating as a receiver. For purposes of illustration, assume that the apparatus 10 of FIG. 1 now is operating as a receiver at the receiver site, with means 64 being set to place apparatus 10 in the receiving mode of operation. Thetransmitted radio waves are received by the antenna included in coupling means 84, and the frequency-modulated signals are detected and converted by modem 76 into pulse signals which, in turn, are applied through lines 77c, 77d to means wherein they are converted into amplitudemodulated signals. As in the transmitting mode of operation, the amplitude levels correspond to the white, gray and black, levels of the graphical information. In

the receiving mode of operation, means 60 in response to the amplitude modulated signals present on lines 68c, 68d provides a corresponding magnetic recording on the surface of tape 12. When all of the transmitted signals are received and processed by the apparatus 10, tape 12 has formed thereon a magnetic image corresponding to the graphical information originally scanned by the transmitter. Tape 12 then is moved fur ther through its orbit, charging apparatus 21 and the scanning means not being operated, and through the toner applying apparatus 25. The toner particles, having a magnetic component, adhere to the surface of tape 12 to form a powder image thereon. Tape 12 is moved past the heads 30 and 38 which are not operated and then moved along with a copy medium such as paper 48 between the rollers 13 and 45. Transfer of the toner particles from tape 12 to paper 48 results, whereupon a copy is made. The toner particles are fixed to the paper 48 by the operation of fusing unit 50. Tape 12 can berecycled, with means60 being deactivated during subsequent cycles, to produce the desired number of copies at the receiving station.

FIG. 3 is a diagrammatic view showing one form of means 60 for scanning the magnetic image on tape 12 when the apparatus 10 is to operate as a transmitter and for forming the magnetic image on tape 12 when the apparatus 10 is to operate as a receiver. Means 60 comprises a rotating helical pole piece 85 and a stationary pole piece 88. The stationary pole piece 88 is in the form of a yoke for providing a return path formagnetic flux through pole piece 85. Pole piece 88 is provided with a coil 90 having leads 91 and 92. Rotating pole piece 85 is positioned within pole piece 88 and is fixed on a shaft 94 which is rotatably connected in pole piece 88 and extends outwardly therefrom for connection to a drive means in the form of an electric motor 96.

Motor 96 is connected through a motor speed control circuit 98 to a source of electrical power 100.

Lines 68a and 68b connect converter 70 through a circuit 102 to the input of an amplifier 104 which is operative during the recording mode of operation. The output of amplifier 104 is connected through leads 91, 92 to coil 90. Lines 106, 107 connect circuit 102 to motor speed control circuit 98 for a purpose to be described. Lines 680 and 68d connect converter 70 directly to the output of an amplifier 108 which is operative during the sensing mode of operation. Lines 91 and 92 connect coil 90 to the input of amplifier 108. Control of amplifiers 104 and 108 during the respective modes of operation is provided by lines 65a and 65b connecting the corresponding amplifiers to means 64.

In operation, during the recording mode amplifier 104 is operated by the control connection through line 65a to means 64, and amplifier 108 is turned off through the control connection provided by line 65b. A magnetic image of graphical information is produced on tape 12 by momentarily energizing coil 90 at properly timed intervals relative to the rotational position of helical pole piece 85. Timing circuit 102 functions to produce a voltage pulse having a time of occurrence relative to the time that pole piece 85 begins to traverse magnetic tape 12 which is dependent upon the amplitude of the incoming signals on lines 68a, 68b. The timed voltage pulses produced by circuit 102 are coupled through amplifier 104 and lines 91, 92 energize coil 90. As the edge of rotating helical pole piece 85 passes by the edge of stationary pole'piece 88, a magnetic signal is recorded in the small region of tape 12 between the edges of pole pieces 85, 88. The frequency of the variation of the amplitude modulated signal on lines 68a, 68b which is applied to timing circuit 102 is much greater than the speed of rotation of helical pole piece 85. The speed of rotation of helical pole piece 85 is synchronized relative to the incoming signals on lines 68a, 68b by virtue of the connection of timing circuit 102 through lines 106, 107 to motor speed control circuit 98. As a result a complete line of properly spaced magnetic image dots or marks is impressed upon tape 12 during each revolution of helical pole piece 85.

During the mode of operation when the magnetic image on tape 12 is to be sensed, amplifier 108 is operated and amplifier 104 turned off by virtue of the controlled connection of these amplifiers through lines 65b and 65a, respectively, to means 64. Motor 96 is operated to rotate helical pole piece 85 as tape 12 is moved relative thereto. As the edge of the rotating pole piece 85 passes by the edge of stationary pole piece 88, the

magnetic signal on tape 12 in the small region thereof where the two pole pieces 85, 88 are close to each other induces a magnetic'signal in the pole pieces. As a result, a voltage is induced in coil90 thereby providing signals which are amplified by amplifier 108 and present on line 68c, 68d connected to the input of converter 70. Helical pole piece 85 can be provided with a small permanent magnet element 110 for producing an initial synchronizing pulse at the beginning of sensing to synchronize operation of the remotely located apparatus which ultimately is to receive the information. The detailed construction and operation of the various circuit components of means 60 for use in facsimile systems, such as circuit 102, are believed to be readily familiar to those skilled in the art, as "indicated in US. Pat. No. 3,l6l,544, so that a detailed description thereof is believed to be unnecessary. Yoke 88 and pole piece 85 should be of a ferrite material capable of transmitting rapid magnetic pulses, i.e., permitting rapid movement of the magnetic domains therein.

FIG. 4 is a diagrammatic view showing another formv 120 each in the form of an elongated rod provided with a v a relatively sharp point at one end and formed from a highly permeable magnetic material such as a nickeliron-colbalt alloy. While only eight stylii are shown in FIG. 4, it is to be understood that a large number of stylii are to be provided along a line or row in a direction transverse to the direction of movement of tape 12. In particular, with tape 12 having a width of 8 '16 inches and with the desired resolution being 0.010 inch, means 60 would include 850 stylii 120 arranged in a row. The sharp pointed ends of stylii 120 are in-contact with or spaced a very small distance from the surface of tape 12. Positioned below tape 12 in the region of the pointed ends of stylii 120 is a member of magnetic material 123. The material of member 123 should be capable of rapid magnetic response, and can be of the same material as that of yoke 88 and pole piece 85 in FIG. 3. Each stylus 120 is provided with a coil wound thereon, and each coil is connected through a common lead 125 to a common ground 126. The coils are connected also through corresponding leads 128 to corresponding outputs of a multiplexer 130. Multiplexers are readily commercially available and well understood by those skilled in the art so that a detailed description of multiplexer 130 is believed to be unnecessary.

Lines 680 and 68b connect converter 70 to the input of an amplifier 132 which is operative during the recording mode of operation. The output of amplifier 132 is connected by means of a line 133 to all of the inputs of multiplexer 130, each multiplexer input corresponding to a particular stylus 120. A line 135 also connects the output of amplifier 132 to the input of a timing circuit 137, the output of which circuit is connected to multiplexer 130 for a purpose to be described. Lines 680 and 68d connect converter 70 directly to the output of an amplifier which is operative during the sensing mode of operation. Signals from multiplexer 130 are applied to the input of amplifier 140 through a line 141, and a line 143 connects multiplexer 130 to amplifier 140 for a purpose to be described. Control of amplifiers 132 and 140 during their respective modes of operation is provided by lines 65a and 65b connecting the corresponding amplifiers to means 64.

In operation, during the recording mode amplifier 132 is operated by the control connecting through lines 65a to means 64, and amplifier 140 is turned off through the control connection provided by lines 65b. A magnetic image of graphical information is produced on tape 12 by selectively energizing proper ones of the stylii 120 along each line of recording on tape 12. The degree of energization of the coil for each stylii 120 is determined by the amplitude level of the signal applied 'to the input of amplifier 132. Synchronization of multiplexer 130 relative to the amplitude modulated signal is provided by a timing circuit 137 in a manner which will be readily apparent to those skilled in the art. As

' induces a magnetic signal in the stylii, and as result voltages are induced in corresponding coils of the stylii thereby providing input signals on leads 128 multi plexer 130 which are amplified by amplifier 140 and present on lines 68c, 68d connected to the input of converter 70. Multiplexer 130 of the present example is designed to provide an initial synchronizing signal at the beginning of a sensing operation which signal is conducted by line 143 to the input of amplifier 140. As a result, during each cycle of operation of multiplexer 130, each line of the magnetic recording on tape 12 is scanned and sensed by means 60 to provide corresponding amplitude modulated signals on lines 68c, 68d.

Tape .12 in the apparatus of this invention preferably comprises a base or substrate of suitable material having a coating of iron oxide and zinc oxide. The base or substrate material must have enough electrical conductivity to allow passage therethrough of electrical charges placed on the exposed surface of the base by charging apparatus 21 to the other surface of the base which is nearer the zinc oxide layer. In particular, one form of tape 12 found to operate satisfactorily consisted of a substrate having a thickness of 0.001 inch coated with either a 0.005 inch layer of gamma iron oxide overlaid by a 0.005 inch layer of zinc oxide or a 0.00l inch layer of a mixture including 30 percent by weight of gamma iron oxide and 70 percent by weight of zinc oxide. in addition, an overcoating of suitable, slightly conductive material having a thickness of about 100 microinches can be provided, being laminated over the iron oxide and zinc oxide matrix. The width of tape 12 is determined by the width of input medium or document 18 and by the width of copies to be made. The number of lines per inch of the magnetic image formed on tape 12 together with the speed of movement of tape 12 in inches per second will determine the frequency of waveform 66 in cycles per second.

The apparatus of the present invention advantageously provides transmission of graphical information between relatively remote transmitting and receiving stations and for making one or a number of hard copies of the graphical information at either or both of the stations. The magnetic image remains on tape 12 after transfer of the toner particles to the copy medium, and therefore the image formed is notvolatile, i.e., not lost in the transfer to the copy medium. This advantageously allows removal of the original at the transmitting station prior to the end of the operation producing hard copies at either station. Furthermore, the retained magnetic image can be utilized to produce additonal copies at a higher speed than that of the first copy and with the original removed from the apparatus. In addition, the foregoing advantages are provided by apparatus which is simple in construction and operation.

Where the input graphical information is from a multiple page document, tape 12 can be made of sufficient length to accommodate successively formed magnetic images of the document pages on the single length of the tape. Then a plurality of copies of the document can be made at either or both of the transmitting and receiving stations, and each copy will be provided with the pages thereof in proper order due to the successively or serially formed magnetic images on tape 12. The pages are then fed to a collating mechanism as used by the printing trades. Since the pages are always in the same order the collating problem is greatly simplified.

While several specific embodiments of the present invention have been described in detail, this has been done for purposes of illustration without thought of limitation.

We claim: a

l. A facsimile system for transferring graphical infor- 'mation between two locations, there being at each location apparatus selectively functioning as a transmitter and a receiver and comprising:

a. storage means having a magnetizable surface for storing a magnetic image of graphical information to be transferred;

b. image forming means for optically scanning an input medium containing graphical information to be transferred and magnetizing said surface in a manner forming a magnetic image of said graphical information on said surface of said storage means when the apparatus is to function as a transmitter;

c. signal generating means for scanning a magnetic image on said surface of said storage means and providing output electrical signals indicative of said graphical information for transmission when the apparatus is to function as a transmitter;

d. signal detecting means for receiving transmitted signs indicative of graphical infonnation and forming a magnetic image of said graphical information on said surface of said storage means when the apparatus is to function as a receiver;

e. transfer means for applying magnetic toner particles to a magnetic image on said surface of said storage. means and for transferring said toner parti cles to a copy medium when the apparatus is to function as a receiver whereby the magnetic image remains on said surface of said storage means for producing additional copies; and

f. coupling means selectively connected to said signal generating means and said signal detecting means for coupling the apparatus to a transmission medium between the two locations.

2. Apparatus according to claim 1, wherein said signal generating means comprises:

a. means for scanning a magnetic image on said storage means and having an output providing signals which are amplitude modulated in accordance with said graphical information;

b. analog to digital converter means having an input connected to the output of said scanning means and an output; and

c. modem means having an input connected to the output of said analog to digital converter means and an output connected to said coupling means for converting the output of said analog to digital converter means to a frequency modulated signal.

3. Apparatus according to claim 1, wherein said signal detecting means comprises:

a. modem means having an input connected to said coupling means and an output for converting frequency modulated signals into digital signals;

b. digital to analog converter means having an input connected to the output of said modem means and an output providing signals which are amplitude modulated in accordance with said graphical information; and

c. means for forming a magnetic image on said storage means and having an input connected to the output of said digital to analog converter means.

i 4. Apparatus according to'claim 1, wherein said copy medium comprises paper and wherein said transfer means comprises means for placing said paper in contact with the surface of said storage means on which said toner particles are present and for causing relative movement between said surface and said paper whereby said particles leave said surface and adhere to said paper. I

5. Apparatus according to claim 1, wherein said storage means is capable of supporting an electrostatic image and wherein said image forming means comprises:

a. means for transforming an optical image of information on an original medium to an electrostatic image on said storage means;

b. means for applying magnetic toner particles to said storage means in a manner such that said particles adhere to said storage means in the form of an image corresponding to the image already present thereon; and

c. magnetic image forming means operatively associated with said storage means for magnetizing said storage means as determined by the location of said toner particles on said storage means to form a magnetic image corresponding to the electrostatic image.

6. Apparatus according to claim 5, wherein said magnetic image forming means comprises: i

a. magnetizing means for applying a continuous magnetic recording to said storage means; and

b. demagnetizing means for selectively erasing said recording according to the location of said toner particles on said storage means to form a magnetic 7 image corresponding to said electrostatic image.

7. Apparatus according to claim 6, wherein said storage means comprises an orbitally movable endless tape, said magnetizing means is located so as to apply said recording to the surface of said tape other than the surface to which said toner particles are adhered, and said demagnetizing means is located so as to apply an erase field toward the surface of said tape on which said toner particles are adhered, whereby said toner particles provide a magnetic shunt for the erase field to form said magnetic image.

8. Apparatus according to claim 5, wherein sa'id storage means comprises an orbitally movable magnetically retentive member capable of surface magnetization, said member having a surface capable of supporting an electrostatic image, and wherein said apparatus further 14 comprises motive means for causing relative displacement between said storage means and said optical image transfonning means, said toner applying means and said magnetic image forming means.

9. In a facsimile system for transferring graphical information between two locations, means for transmitting signals indicative of said graphical information between said locations comprising:

a. storage means being magnetizable and capable of supporting an electrostatic image;

b. means for transforming an optical image of graphical information on an original medium to an elec- 5. V

trostatic image on said storage means;

c. means for applying magnetic toner particles to said storage means in a manner such that said particles adhere to said storage means in the form of an image corresponding to the image already present thereon;

d. magnetic image forming means operatively associated with said storage means for magnetizing said storage means as determined by the location of said toner particles on said storage means to form a magnetic image corresponding to the electrostatic image;

. transfer means for transferring said toner particles from said storage means to a copy medium whereby a copy of the original is made and the magnetic image remains on said storage means;

f. motive means for causing relative displacement between said storage means and said optical image transforming means, said toner applying means, said magnetic image forming means and said transfer means;

g. signal generating means for scanning the magneticimage on said storage means and providing output electrical signals indicative of said graphical information for transmission; and

h. coupling means'connected to said signal generating means for coupling the apparatus to a transmission medium between the two locations.

10. Apparatus according to claim 9, wherein said magnetic image forming means comprises:

a. magnetizing means for applying a continuous magnetic recording to said storage means; and

b. demagnetizing means for selectively erasing said recording'according to the location of said toner particles on said storage means to form a magnetic image corresponding to said electrostatic image.

11. Apparatus according to claim 10, wherein said storage means comprises an endless tape, said magnetizing means is located so as to apply said recording to the surface of said tape other than the surface to which said toner particles are adhered, and saiddemagnetizing means is located so as to apply an erase field toward the surface of said tape on which said toner particles are adhered, whereby said toner particles provide a magnetic shunt for the erase field to form said'rnagneticimage.

1i l I i 

1. A facsimile system for transferring graphical information between two locations, there being at each location apparatus selectively functioning as a transmitter and a receiver and comprising: a. storage means having a magnetizable surface for storing a magnetic image of graphical information to be transferred; b. image forming means for optically scanning an input medium containing graphical information to be transferred and magnetizing said surface in a manner forming a magnetic image of said graphical information on said surface of said storage means when the apparatus is to function as a transmitter; c. signal generating means for scanning a magnetic image on said surface of said storage means and providing output electrical signals indicative of said graphical information for transmission when the apparatus is to function as a transmitter; d. signal detecting means for receiving transmitted signs indicative of graphical information and forming a magnetic image of said graphical information on said surface of said storage means when the apparatus is to function as a receiver; e. transfer means for applying magnetic toner particles to a magnetic image on said surface of said storage means and for transferring said toner particles to a copy medium when the apparatus is to function as a receiver whereby the magnetic image remains on said surface of said storage means for producing additional copies; and f. coupling means selectively connected to said signal generating means and said signal detecting means for coupling the apparatus to a transmission medium between the two locations.
 2. Apparatus according to claim 1, wherein said signal generating means comprises: a. means for scanning a magnetic image on said storage means and having an output providing signals which are amplitude modulated in accordance with said graphical information; b. analog to digital converter means having an input connected to the output of said scanning means and an output; and c. modem means having an input connected to the output of said analog to digital converter means and an output connected to said coupling means for converting the output of said analog to digital converter means to a frequency modulated signal.
 3. Apparatus according to claim 1, wherein said signal detecting means comprises: a. modem means having an input connected to said coupling means and an output for converting frequency modulated signals into digital signals; b. digital to analog converter means having an input connected to the output of said modem meaNs and an output providing signals which are amplitude modulated in accordance with said graphical information; and c. means for forming a magnetic image on said storage means and having an input connected to the output of said digital to analog converter means.
 4. Apparatus according to claim 1, wherein said copy medium comprises paper and wherein said transfer means comprises means for placing said paper in contact with the surface of said storage means on which said toner particles are present and for causing relative movement between said surface and said paper whereby said particles leave said surface and adhere to said paper.
 5. Apparatus according to claim 1, wherein said storage means is capable of supporting an electrostatic image and wherein said image forming means comprises: a. means for transforming an optical image of information on an original medium to an electrostatic image on said storage means; b. means for applying magnetic toner particles to said storage means in a manner such that said particles adhere to said storage means in the form of an image corresponding to the image already present thereon; and c. magnetic image forming means operatively associated with said storage means for magnetizing said storage means as determined by the location of said toner particles on said storage means to form a magnetic image corresponding to the electrostatic image.
 6. Apparatus according to claim 5, wherein said magnetic image forming means comprises: a. magnetizing means for applying a continuous magnetic recording to said storage means; and b. demagnetizing means for selectively erasing said recording according to the location of said toner particles on said storage means to form a magnetic image corresponding to said electrostatic image.
 7. Apparatus according to claim 6, wherein said storage means comprises an orbitally movable endless tape, said magnetizing means is located so as to apply said recording to the surface of said tape other than the surface to which said toner particles are adhered, and said demagnetizing means is located so as to apply an erase field toward the surface of said tape on which said toner particles are adhered, whereby said toner particles provide a magnetic shunt for the erase field to form said magnetic image.
 8. Apparatus according to claim 5, wherein said storage means comprises an orbitally movable magnetically retentive member capable of surface magnetization, said member having a surface capable of supporting an electrostatic image, and wherein said apparatus further comprises motive means for causing relative displacement between said storage means and said optical image transforming means, said toner applying means and said magnetic image forming means.
 9. In a facsimile system for transferring graphical information between two locations, means for transmitting signals indicative of said graphical information between said locations comprising: a. storage means being magnetizable and capable of supporting an electrostatic image; b. means for transforming an optical image of graphical information on an original medium to an electrostatic image on said storage means; c. means for applying magnetic toner particles to said storage means in a manner such that said particles adhere to said storage means in the form of an image corresponding to the image already present thereon; d. magnetic image forming means operatively associated with said storage means for magnetizing said storage means as determined by the location of said toner particles on said storage means to form a magnetic image corresponding to the electrostatic image; e. transfer means for transferring said toner particles from said storage means to a copy medium whereby a copy of the original is made and the magnetic image remains on said storage means; f. motive means for causing relative displacement between said storage means and said optical image transforming means, said tOner applying means, said magnetic image forming means and said transfer means; g. signal generating means for scanning the magnetic image on said storage means and providing output electrical signals indicative of said graphical information for transmission; and h. coupling means connected to said signal generating means for coupling the apparatus to a transmission medium between the two locations.
 10. Apparatus according to claim 9, wherein said magnetic image forming means comprises: a. magnetizing means for applying a continuous magnetic recording to said storage means; and b. demagnetizing means for selectively erasing said recording according to the location of said toner particles on said storage means to form a magnetic image corresponding to said electrostatic image.
 11. Apparatus according to claim 10, wherein said storage means comprises an endless tape, said magnetizing means is located so as to apply said recording to the surface of said tape other than the surface to which said toner particles are adhered, and said demagnetizing means is located so as to apply an erase field toward the surface of said tape on which said toner particles are adhered, whereby said toner particles provide a magnetic shunt for the erase field to form said magnetic image. 